1. Field of the Invention
The present invention relates to a technique of remotely controlling a controlled apparatus in accordance with the distance between a controlling apparatus and the controlled apparatus.
2. Description of the Related Art
Recently, controlling apparatuses typified by remote controllers have started to allow various remote manipulations with respect to controlled apparatuses. With regard to a digital TV set, a remote controller allows the user to perform operations, for example, initial setting, recording, playback, charging, authentication, Web browsing, and the transmission/reception of electronic mail, in addition to general TV viewing operation.
The application of a ranging technique to home appliances has been proposed. Japanese Patent Laid-Open No. 2000-152 has proposed an invention designed to provide a ranging function for a TV receiver and warn a viewing audience not to move closer to the TV receiver when the distance between the viewing audience and the TV receiver becomes too short. In addition, Japanese Patent Laid-Open No. 2004-096599 has proposed a remote control system which entirely invalidates operation by a remote controller if the distance to a viewing audience is shorter than a predetermined distance, and entirely validates operation by the remote controller if the distance is longer than the predetermined distance. This aims at preventing children and the like from developing myopia or epilepsy.
Recently, providing multiple functions to a remote controller has caused various problems. A digital TV set allows the user to subscribe to a VOD (Video On Demand) service and change various passwords through a remote controller. If, therefore, a child or the like mischievously operates the remote controller and unintentionally subscribes to a pay service or changes a password, the subscriber will suffer a financial loss.
The inventions disclosed in patent references 1 and 2, however, can only prevent a viewing audience from moving closer to the TV receiver. The invention disclosed in patent reference 2, in particular, is only configured to entirely inhibit the operation of the remote controller or entirely permit the operation in accordance with whether the distance is short or long.
It is convenient if the user can change the contents of operation which he/she can perform through a remote controller in accordance with the distance between a controlled apparatus and a controlling apparatus. It is also convenient if the contents of processing to be executed in a controlled apparatus change in accordance with the distance to the apparatus at the time of operation even when the user operates the same button.
Consider an enlargement/reduction button for a TV screen. For example, when the user presses this button from a place far from the TV set, the enlargement ratio is set to 200%. When the user presses the button from a place close to the TV set, the enlargement ratio is set to 120%. In this case, the merit of this technique is that operating the remote controller at a long distance can greatly enlarge the screen at once, and operating the remote controller at a short distance can gradually enlarge the screen.